In 1817, James Parkinson described Parkinson's disease as paralysis agitans. The most common symptoms for paralysis agitans are constant tremors in the hands and legs, body movements that become stiff, slow and weak with near paralysis, and sober-mask like facial expressions. Patients suffering with this disease have difficulty in maintaining an erect posture as they often have a stooped appearance, and they lean forward while walking with a shuffling gait.
The pathological cause of Parkinson's disease involves destruction of the nerve cells in the substantia nigra part of the brain, the part of the brain involved with muscle movements. The nerve cells of the substantia nigra use an in vivo chemical dopamine for transmitting signals between each other, and it is the absence of dopamine that leads to Parkinson's symptoms. Consequently, present medical treatment for Parkinson's disease comprises administering a drug that acts on the basal ganglia to exert a dopaminergic or an anticholinergic effect, or administering a drug that substantially lessens or blocks the body's monamine oxidase from metabolizing nerve cell dopamine. The medical history of Parkinson's disease is presented in The Pharmacological Basis of Therapeutics, by Goodman and Gilman, 7th Ed., Chap. 21, (1985), published by Macmillan Publishing Company, N.Y. The drugs administered by the prior art for treating Parkinson's disease are administered usually from a tablet or a capsule. These forms deliver a drug in a bulk, non-rate uncontrolled dumping dose that is subject also to the changing adverse environment of the gastrointestinal tract.
In the light of the above presentation, it will be appreciated by those versed in the drug dispensing art to which this invention pertains, that a pressing need exists for a dosage form that can administer a drug for treating Parkinson's disease at a controlled rate in a constant dose per unit time over a prolonged period of time. The need exists for an oral dosage form that can administer an anti-Parkinson's disease drug for its therapeutic dopaminergic, anti-cholinergic, or anti-monoamine oxidase effect substantially independent of the variable environment of the gastrointestinal effect. It will be appreciated further by those versed in the dispensing art, that such a novel and unique dosage form that can administer an anti-Parkinson's disease drug in a rate controlled dose over time, and simultaneously provide therapy in the brain, would represent an advancement and a valuable contribution to the art.